Auto-generate an IPv6 link-local address based on the NIC's MAC Address.

This change adds support for optionally auto-generating an IPv6 link-local
address based on the NIC's MAC Address on NIC enable.

Note, this change will not break existing uses of netstack as the default
configuration for the stack options is set in such a way that a link-local
address will not be auto-generated unless the stack is explicitly configured.
See `stack.Options` for more details. Specifically, see
`stack.Options.AutoGenIPv6LinkLocal`.

Tests: Tests to make sure that the IPb6 link-local address is only
auto-generated if the stack is specifically configured to do so. Also tests to
make sure that an auto-generated address goes through the DAD process.
PiperOrigin-RevId: 276059813

1 files changed, 68 insertions, 0 deletions

diff --git a/pkg/tcpip/header/eth_test.go b/pkg/tcpip/header/eth_test.go
new file mode 100644
index 000000000..6634c90f5
--- /dev/null
+++ b/pkg/tcpip/header/eth_test.go
@@ -0,0 +1,68 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package header
+
+import (
+	"testing"
+
+	"gvisor.dev/gvisor/pkg/tcpip"
+)
+
+func TestIsValidUnicastEthernetAddress(t *testing.T) {
+	tests := []struct {
+		name     string
+		addr     tcpip.LinkAddress
+		expected bool
+	}{
+		{
+			"Nil",
+			tcpip.LinkAddress([]byte(nil)),
+			false,
+		},
+		{
+			"Empty",
+			tcpip.LinkAddress(""),
+			false,
+		},
+		{
+			"InvalidLength",
+			tcpip.LinkAddress("\x01\x02\x03"),
+			false,
+		},
+		{
+			"Unspecified",
+			unspecifiedEthernetAddress,
+			false,
+		},
+		{
+			"Multicast",
+			tcpip.LinkAddress("\x01\x02\x03\x04\x05\x06"),
+			false,
+		},
+		{
+			"Valid",
+			tcpip.LinkAddress("\x02\x02\x03\x04\x05\x06"),
+			true,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			if got := IsValidUnicastEthernetAddress(test.addr); got != test.expected {
+				t.Fatalf("got IsValidUnicastEthernetAddress = %t, want = %t", got, test.expected)
+			}
+		})
+	}
+}